Bridge-spring action for oscillating-platen presses



' (No Model.)

J. THOMSON.

BRIDGE SPRING ACTION FOR OSGILLATING PLATEN PRESSES.

No. 373,571. Patented Nov. 22, 1887.

UNITED STATES ATENT FFICEQ JOHN THOMSON, OF BROOKLYN, NEW YORK, ASSIGNORTO THE COLTS PATENT FIRE ARMS MANUFACTURING COMPANY, OF HARTFORD,

CONNECTICUT.

BRIDGE-SPRING ACTION FOR OSCILLAIING-PLATEN PRESSES.

SPECIFICATION forming part of Letters Patent No. 373,571, dated November22, 1887.

(No modelil To all whom it may concern.-

Be it known that 1, JOHN THOMSON, a citizen of the United States,andaresident of the city of Brooklyn, Kings county, State of New York,have invented certain new and useful Improvements in Bridge-SpringActions for Oscillating-Platen Presses, of which the following is aspecification.

This invention consists in a device for controlling the platen action ofjaw-presses of that class in-which the platen is caused to slidedirectly to or from the bed prior and subsequent to the instant ofimpression, but during all other portions of its action to roll on atable or seat.

The figure of the drawing represents a vertical end elevation ofsuch aplaten action,showing the application of my invention, in which thenumeral 3 represents the bed; 4, the side frame; 5, the rocker-seat; 6,the platen; 7, the rocking block or bridge; 8, the rocker; 9, the ear ofsaid rockingblock, and 10 the lugs forming a part of the ear, and whichengage the rocker-seat during the direct sliding action. Motion isimparted to the block by a connectingrod, 11, journaled on theblockshaft 12, the extension of said connecting-rod being connected withthe power member-- such as a crank or toggle arranged to impart areciprocating motion to the rod-all as in common practice.

The usual mode of controlling the motion of such rocking blocks is topivot a link, as 13, to the block, as at 14, the extension of the linkbeing guided in a barrel containing a spiral spring, and thebarrelfixedly journaled to the frame, the spring, thus acting directly in theplane 15 of the link,exerting its tension between the link and thebarrel. The function of the spring is to permit the block and platen tobe drawn forward, as represented by dotted outline 16, but to thereafteractas a fixed member, free to vibrate with the block and to cause theblock to roll properly.

The objections to such arrangements are, first, in that the availablespace directly under the block is exceedingly limited; second, thespring or springs require to be exceedingly powerful. and, inconsequence of the limited space, of incorrect proportions.

. The reason why such powerful springs are required to control a rockingmotion, so called, has not usually been understood, and hence hasresulted in the use of springs entirely inadequate for the requiredduty. The said reason is that the center 14, if permitted to act freelywith the rocking block, would describe the are ofa cycloidal curve, as17, in constructing which the rocker8 is the describing circle, whosecenter is at 18; but as the link which swings on the center 19 describesthe arc of a circle, as 20, and the rocker is forced to partake of themotion of the link, it is evident that the rocker rolls and grindsdifferentially, like a differential mill; and in consequence of this andthe usual weight of such rocking blocks and platens, great friction isthereby developed. To meet these difficulties in the best manner by theuse of a spring action, I mount the heel 19 of the link in a lever, 21,which lever is journaled at 22 in the frame. pivotally connected to aslide-rod, 23. A retaining-rod, 24, or two rods, one on either side ofthe slide-rod,is also pivotally connected to the frame, as at 25, havinga slide, 26, fixedly secured to the said rod or rods, which acts as aguide to the slide -rod 23.

Between the slide and the nut 27 and upon the slide-rod is mounted aspring, 28, which acts by extension to normally hold the lever againstthe stop 29. The consequence of this arrangement is that the spring maybe given any desired control of the bridge, either by proportion ofleverage or by extent of spring, or both, as this construction anddisposal of the parts in a usually-unoccupied space permits the use of aspring and lever of ample proportions for the required duty.

The broken line 30 indicates the center of the lever when the platen ison theimpression, while the line 31 and outline 32 indicate the positionof the link and block at the extreme ofthe rocking action.

The arrangement of the link shown in the figure represents its besttheoretical positionthat is, in which the arc of the circle 20 and thearc of the cycloid 17 intersect at the beginning and end of the action.In this wise the slip is reduced to the minimum; but in specialinstances it is required to increase this slip. In this device this maybe readily ac The extension of the lever 22 is complished by simplyraising or lowering the center 33 of the lever, the eflect of which isto cause the path of the circle 20 to pass within or beyond the presentintersecting point 34:.

5 The precise arrangement here shown may be departed from withoutaffecting the principle and advantages of this invention-as, forinstance, the lever 21, having its journal at 22, and bearingfor theheel of the link, as

IO shown, might be projected to form a bellcrank by the extension 22*,the spring-connection being vertical or at any angle where the springsmight be best arranged; also that a plurality of springs may be used,instead of 15 the single spring shown in the drawing.

I claim- 1. The combination of the rocking block,

JOHN THOMSON. l Witnesses:

WILLIAM THOMSON, v OLIVER N. PAYNE.

